Dne 16.11.2018 v 12:10 Jenny TC napsal(a):
> On startup, applications such as PulseAudio or CRAS enable playback or
> capture on all PCM devices to verify that configurations are correct,
> and close them immediately. For DMICs, this can result in the clock
> being turned off very quickly, which may not compatible with internal
> state machine transition requirements.
>
> This patch add a mode-switch delay which will prevent the clock from
> being turned off without complying with manufacturer timing
> specifications. While the DMIC clock may be controlled at a lower level,
> be it with hardware or firmware, applying the delay during the
> STOP_TRIGGER phase ensures that there is no race condition, e.g. with
> the hardware/firmware turning off the clock earlier
>
> Signed-off-by: Sathyanarayana Nujella <sathyanarayana.nujella@xxxxxxxxx>
> Signed-off-by: Jairaj Arava <jairaj.arava@xxxxxxxxx>
> Signed-off-by: Harsha Priya <harshapriya.n@xxxxxxxxx>
> ---
> sound/soc/codecs/dmic.c | 31 +++++++++++++++++++++++++++++++
> 1 file changed, 31 insertions(+)
>
> diff --git a/sound/soc/codecs/dmic.c b/sound/soc/codecs/dmic.c
> index 8c4926d..0527bc2 100644
> --- a/sound/soc/codecs/dmic.c
> +++ b/sound/soc/codecs/dmic.c
> @@ -30,9 +30,35 @@
> #include <sound/soc.h>
> #include <sound/soc-dapm.h>
>
> +static int modeswitch_delay_ms;
> +module_param(modeswitch_delay_ms, uint, 0644);
> +
> struct dmic {
> struct gpio_desc *gpio_en;
> int wakeup_delay;
> + /* Delay after DMIC mode switch */
> + int modeswitch_delay_ms;
> +};
> +
> +int dmic_daiops_trigger(struct snd_pcm_substream *substream,
> + int cmd, struct snd_soc_dai *dai)
> +{
> + struct snd_soc_component *component = dai->component;
> + struct dmic *dmic = snd_soc_component_get_drvdata(component);
> +
> + switch (cmd) {
> + case SNDRV_PCM_TRIGGER_STOP:
> + if (dmic->modeswitch_delay_ms)
> + mdelay(dmic->modeswitch_delay_ms);
> +
> + break;
> + }
> +
> + return 0;
> +}
> +
> +static const struct snd_soc_dai_ops dmic_dai_ops = {
> + .trigger = dmic_daiops_trigger,
> };
>
> static int dmic_aif_event(struct snd_soc_dapm_widget *w,
> @@ -68,6 +94,7 @@ static int dmic_aif_event(struct snd_soc_dapm_widget *w,
> | SNDRV_PCM_FMTBIT_S24_LE
> | SNDRV_PCM_FMTBIT_S16_LE,
> },
> + .ops = &dmic_dai_ops,
> };
>
> static int dmic_component_probe(struct snd_soc_component *component)
> @@ -85,6 +112,10 @@ static int dmic_component_probe(struct snd_soc_component *component)
>
> device_property_read_u32(component->dev, "wakeup-delay-ms",
> &dmic->wakeup_delay);
> + device_property_read_u32(component->dev, "modeswitch_delay_ms",
> + &dmic->modeswitch_delay_ms);
This should be probably consistent with the previous property name. Use
"modeswitch-delay-ms".
> + if (modeswitch_delay_ms)
> + dmic->modeswitch_delay_ms = modeswitch_delay_ms;
>
> snd_soc_component_set_drvdata(component, dmic);
>
>
Jaroslav
--
Jaroslav Kysela <perex@xxxxxxxx>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.
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